Devices for applying a mat of aggregate material, such as crushed stone, on a surface in preparation for subsequent paving are generally well known in the art. For example, an asphalt paving machine, when operated with crushed stone instead of hot mix asphalt material, may be used to apply a base layer of crushed aggregate prior to the placement of hot mix asphalt over the prepared base. A properly prepared and applied base layer will greatly improve the service life of the final layer of asphalt pavement.
In many instances, it is desirable to have an additive entrained substantially uniformly throughout the crushed aggregate material. The most common additive is water, although in some circumstances it may be desirable to add liquid emulsifying agents or dry additives such as lime. Typically, the additive is mixed into the aggregate material in a pug mill and then transferred to the paving machine for application on the ground.
Unfortunately, it is very difficult, if not impossible, to control the moisture content of the aggregate mix using conventional methods. Evaporation of the entrained water between the pug mill and the paver is affected by many variables, such as ambient temperature and humidity conditions, the distance from the pug mill to the paver, and the amount of handling of the aggregate mix. Accordingly, there exists a need for an improved device for injecting liquid or dry additives into a mix of aggregate material.